Method of forming ceramic articles and producing different colors or shades along different portions of the article



Aug. l, 1950 R. w. ERDLE 2,517,100

l METHOD 0F FORMING CERAMIC ARTICLES AND PRODUCING DIFFERENT COLORS OR SHADES ALONG DIFFERENT PoRToNs oF THE ARTICLE Filed March 2s, 194e VIN1/mmm. Eeuzgr EYE/de,

BY l JMW/Jun, mu /w of course. is undesirable.

Patented ug. 1, 1950 METHOD OF FORMING `CERAMIC! ARTICLES AND PRODUCING DIFFERENT ICOLOR/S OR SHADES ALONG DIFFERENT PORTIONS OF THE ARTICLE Reiner W. Erdle, Chicago, Ill., assignor to Dental Research Corporation, Chicago, Ill., a corporation of Illinois Application March 23, 1946, Serial No. 656,750

8 Claims.

This invention relates, in general, to a method of forming ceramic articles and producing difierent colors or shades along diiTerent portions of the article, and has particular relation to an improved method of forming artiiicial teeth and producing throughout the run of teeth diierent shades along different portions of the teeth accurately to match a standard shade guide or the natural teeth.

The present application is a division of my copending application Serial No. 525,012, filed March 4, 1944, now Patent No. 2,406,208, which relates to the article and the material for forming the same.

Heretofore, in order to produce different shades or colors in different parts of an artificial tooth, porcelaine of different colors were manufactured.

Porcelain powders of diilerent colors were mixed with distilled water or a suitable binder into separate porcelain mixes, one for each color.

`The lighter color porcelain mix, and a definite amount of it, was placed in the tooth cavity of the mold. By gravity or vibration, for example, in the manner set forth and claimed in my prior U. S. Patent No. 2,196,258, issued April 9, 1940,

of the mold cavity and form, for example, the incisal part of the tooth. The second color mix of porcelain having, for example, the color of the middle third or middle section of the toothent colored porcelain mixes to produce a tooth` having the desired shades along the different parts thereof. It was found that by carefully `mixing the colored porcelain powders, two different colored porcelain mixes could be used to produce a porcelain tooth of a given shade.

In order to produce a given shade in a porthis porcelain mix would flow to the lower part i celain tooth with two or more diiTerent colored `porcelains the operator must exercise extreme care to put the proper amount of the diilerent colored porcelain mixes into the tooth mold.

`The time element is also of great importance.

If too much time elapses between the operations of lling the mold with the different `porcelain colors, a sharp line will appear on the tooth caused by the diiTerent colored porcelain mixes. If there is insuiiicient time between the iilling operations, the porcelain colors will run together in the tooth mold and the porcelain tooth so produced will have substantially one color. This,

In handling two or more porcelain mixes which have different colors, considerable time is consumed and the results depend upon the skill of the operator. Teeth are `produced in this manner in dilerent dental laboratories throughout the country and in other countries. They have to match a standard or given shade guide, and

`because the resulting shading of a tooth. depends to a large extent on the skill of the `operator it has been difficult to obtain reasonably accurate matches of manufactured teethV with a standard or given shade guide.

My copending application above identified discloses in its more specific aspects a unitary ground porcelain` material comprising differentially ground particles of porcelain initially,

and prior to grinding, of diierent colors and in `which the differentially -ground porcelain parproduce the desired color along the incisal portion of the tooth, a gingival portion formeduof relatively finer ground porcelain particles initially, and prior to grinding, of relatively darker color to produce a different color along the gingival portion of the tooth, and,` if desired,` an intermediate portion formed of relatively intermediate ground porcelain particles initially, and prior to grinding, `of a relatively intermediate `color to produce an intermediate color along the intermediate portion of the tooth.

According to the more specific aspects of the present invention, I produce the `porcelain tooth or other ceramic article and the different shades or colors along different portions thereof by forming a unitary ground porcelain mix comprising differentially ground particles Iof porcelain initially and prior to grinding of different colors and in which the differentially ground porcelain particles, initially of diierent colors, are combined in proportions adaptedto produce by the diierent settling characteristics of the diierent size particles a predetermined shaded color- =ing effect in an article formed of the material,

filling the tooth cavity of the mold with this unitary porcelain mix, and vibrating the porcelain mix in the mold cavity to settle the coarser porcelain particles in the `bottom of the mold cavity to produce the desired Shade along the irl--` Another advantage of theinventicn is' in theability to provide for automatically shading a tooth correctly, thereby raising the standard of the teeth.

Another advantage of the invention isthe ability to provide for producing a tooth with its dilerent parts of different shades from a single or unitary. porcelain rnix, thereby reducing the laborv cost and eliminatingany error an operator may make in handling two or more different 'colored' porcelain mixes to ill the tooth mold .y

cavity..

Another object of theainvention is in the. ability to.` avoid. the necessity for separate` differently colored porcelain mixes.; also` 1filling of the mold cavity by successive operations with the disadvantages already described.

Another advantage of the. invention is in the ability to assure alY better shading of the porcelain. teeth, and that the-diferent shades in difyferent partsof each tooth of a. commercial run .f

of teeth will Lmiformly and accurately match a standard or given shade guide.

Further advantages ci the invention will` be apparent from the following detailed description taken in connection with thel accompanying drawing.l

In the drawing:A

Figure liis a microenlargement showing a typical section of a porcelain powder embodying t -e present invention;

Figure- 2" shows more or less diagrammatically ya mold having a tooth. cavity filled withy the single or unitary porcelainrnixof the presentinvention; and f Figure 31 is anenlarged perspective view of a tooth formed according to. the present invention. Referring tothe more or less diagramrnaic illustrations in the'drfayving, I provide according to the present inventiona unitary ground' porcelaint comprisingdiiierentially ground particles of porcelainy initially, and prior to grinding, of diii ferent colors and in. which the differentially ground porcelain particles initially` of diierent colors are combined in proportions'. adapted to produce by the different settling characteristics ot the different size particles av predetermined shaded coloring effect in. an article formed of the material. i

As shown diagrammatically in Figure l, this new and improved porcelain has relatively coarse porcelain particles lll made of a lighter shade '1' porcelain having, for example, the .color oi the incisal part of' the'tooth. It also has liner porcelain `particles I l., and still ner porcelain particles li. rEhe particles il, which are of a grain size next smaller than the grain size of the particles lil, are made ci a darker shade having the 'color ofthe middle part of the tooth. 'Iheparticles If:v of next smaller grain size are made ofa 'still darker shade, having the color of thegingi- 'Val'part offthetoothg" i i '1 The particles it, li and E2 of different colors or shades and different sizes, and in predetermined amounts, are mixed together to produce a single porcelain powder having all of the colors or shades required in a porcelain tooth. rlhe single porcelain mix. is produced by thoroughly mixing this mixture of porcelain particles I9, Il and l2 with a deiinite amount of distilled water or a suitable binder to produce a single porcelain mix of the desired consistency and having all of the required colors of shades in the single porcelain mix.

The tooth cavity i3 of the mold is then iilled with this single or unitary ground porcelain mix as shown at l5, thus introducing all of the representative lotsl of porcelain particles ID, ll and i2 into thev cavity i3 completely to fill the same in a single operation and without successively introducing porcelain mixes of diiierent colors into diierent parts of the mold cavity as heretofore required. The porcelain mix I5 is preferably introduced into the mold cavity i3 While allu oi the various porcelain particles itl, ll and l2; are in complete suspension in the Water or binder.. This assures the desired shading of the tooth,` and also assures that the different shades in diiferentparts of each toothof; acommercial run o1,A teeth will accurately and uniformly match, for example, a standard or given shade guide.

Allof the. porcelain particles lil, H and lf2: of

Vdierent colors and diierent grain sizes may be .19431, although, of course this. may within the scope or. the present invention.

Upon filling, the mold cavity 1:3 with the single porcelainmix, the rnold i4 and porcelain mix t5 in the cavity it thereof are vibr.ated,ior example, asmor'e: fullyk described and. claimed in my prior U. S. Patent No. 2,196,258, issued April 9., 194D.

Vibrating means for this. purpose is shovvnmore or lessv diagrammatically at i6, The particular manner in which the desired vibration is secured 'and` the particular form of thevibrating means may of course vary. widely.

Thediiierent size porcelain particles I0, l'r l and l2' have different` settling characteristics.. The particles Ill, which are coa-rser or.v of larger grain size, will settle at once to the bottom oi the: mold cavity i3; The next liner particles ll' settle over the coarser particles lil, and Where particles l2 of a thirdgrainsize are employed-these still ner particles I2 settle over the particles Il!" of intermediate grain size. In 'this manner the correctly colored porcelain particles pack into the proper parts of the mold cavityi3 to produce, by the different settling or packing characteristicsl of the different. size particles, the different colors or shades in the diiierent parts of the tooth. The iin-er particles will ill in the spaces between the coarser particles to produce an accurate and uniform overall blending of colors, so that the resulting tooth will follow the shade of natural teeth.

After the tooth as shown at il in Figure 3 is removed from the mold lil, it may be dried and fire-hardened and glazed, as more fully disclosed in my previously mentioned U. S, Patent No.

2,i9,258. -rh porleiam teo-afin A@elected `for illustration is ananterior tooth, lbut of course this may vary. Theiincisal part llgofi thetooth Il is formed bycthelcoarser Agrainparticles l having the `color ofthe incisal shadeof the. tooth. The middle part 2t: of the toothis formed bythe next finer particles il having the color of the middle part of the tooth. f1 The gingival part `2l is formed by the nextnerparticles-IZ' having the color of the gingival part of the tooth.

From the foregoing descriptionit will 'now be apparent that the useof the single oriunitary mix porcelain and forming rofl the tooth, by the present invention havethe advantage ofautomatically shading a tooth correctly,lthereby raising the standard of teeth producedj according to the present invention. f The filling" of the `tooth mold cavity i3 involvesthe handling oi only one porcelain mix, which reduces considerably the labor cost for producing porcelain teeth. The use of the `single or unitary mix porcelain also eliminates any error an operator can make by handling two or morediiierent coloredporcelains to i'lll a tooth mold cavity by successive filling operations. As a result, I secure better shading or coloring ofthe tooth, and l'lassure uniform and accurate matching of alliteeth of algiven commercial run of teeth with a standard -or `given shade guide.

If desired, some of the porcelain particles l@ may be uncolored and other of such particles ill may be colored to shade the incisal part of the tooth by a blanding of the colored and uncolored poreclain. Likewise some of the porcelain particles Il and/or some of the particles l2 may be uncolored and other of such particles may be colored to shade the tooth along its middle and gingival parts by a blending of these colored and uncolored porcelain particles.

One suitable porcelain for purposes of the present invention is composed of minerals and, mainly, of nepheline syenite, as more fully described in my prior U. S. Patent No. 2,334,319, issued November 16, 1943. This particular material is referred to for purposes of illustration, it being understood that other ceramic materials and like materials may be employed within the scope of the broader aspects of the present invention.

The embodiment of the invention shown in the drawings is for illustrative purposes only, and it is to be expressly understood that the drawing and the accompanying specilication are not to be construed as a definition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

I claim:

1. The method of forming an article of comminuted material and producing diiierent shades along diierent portions thereof, which comprises applying different colors to diierent batches of the material prior to reducing same to comminuted form, reducing the different batches of differently colored materials to comminuted form with the particles of the different batches of different grain sizes, combining the dilerently colored particles of diiierent grain sizes together and with a liquid to form a unitary mix, introducing said mix into the cavity of a mold, and irnposing a vibrating action upon the unitary mix in the mold cavity to settle the coarser particles beneath the ner particles, whereby to produce different shades along different portions of the article and to compact the material to the form different shades alongdiferent portions of the:

teeth, whichl comprisesapplying diilerent colors to diierent `.batches ofA theporcelain material prior to reducing same to comminuted 'form,fre= ducing the dierent batches of diilerentlycol` oredlporcelain material to comminuted form with the particles oi the diierent batches of different grain sizes, combining the differently colored par-1 ticles of vdifferent grain sizesltogetlier and with a liquid. to form aunitaryiporcelain mix, intro-y ducing said `mix into the tooth cavity of l a mold, and imposing a vibrating `action upon the unitary mix inthe mold cavity to settlethe coarserparticles beneath the linerparticles,` whereby to pro,-` duce diierent shades alongzd-iierent portions` of the tooth and to compact the' material to the form ofa firm body of a shape corresponding to the` shape `of the tooth cavity of the mold.

3. The? method of forming porcelain` teeth of comminuted porcelain material` and,y producing diierent shades along diiierent portions of` the teeth, which comprises applying diierent `c olors to at least three different `batches of porce-A lain materialprior to reducing same to` comminuted, form, reducing the dierent :batches of, differently colored porcelain material to comminuted form with the particles of the three diiferent batches of relatively ne, intermediate, and relatively coarse grain sizes respectively, combining the differently colored particles of relatively line, intermediate, and relatively coarse grain sizes together and with a liquid to form a unitary porcelain mix, introducing said mix into the tooth cavity of a mold, and imposing a, vibrating action upon the unitary mix in the mold cavity to settle the relatively coarse particles at the bottom, the particles of intermediate grain size above said relatively coarse particles, and the relatively ne particles above said particles of intermediate grain size, whereby to produce dierent shades along different portions oi the tooth and to compact the material to the form of a nrm body of a shape correspending to the shape of the tooth cavity of the mold.

4. The method of forming an article of comminuted material and producing different shades along different portions thereof, which comprises combining a plurality of batches of comminuted material with the particles of different batches of different grain sizes and of different colors and with a liquid to form a unitary mix, introducing said mix into the cavity of a mold, and imposing a vibrating action upon the unitary mix in the mold cavity to settle the coarser particles beneath the finer particles whereby to produce diiferent shades along different portions of the article and to compact the material to the form of a rm body of a shape corresponding to the shape of the mold cavity.

5. The method of forming porcelain teeth ol' comminuted porcelain material and producing different shades along different portions of the teeth, which comprises combining a plurality of batches of comminuted porcelain material with the particles of diiierent batches oi dierent grain sizes and of different colors and with a liquid to form a unitary mix, introducing said mix into the tooth cavity of a mold, and imposing a vibrating action upon the unitary mix in thev mold: cavity-tozsettle the coarser particles beneath the liner particleswwherebyf'to' produce different shades@alongdifferent portionsfof the tooth and to: compact thef material tog. theiorm. ofL a, rm: body of a; shape.. corresponding;Y tothe shape of theltooth cavity` oizthe' mold:

6.,The method of ormingporcelain; teeth ofi cornrninutedV porcelain materialand producing, diierentrshades along, differentA portions of: the teeth,y which. comprises combining', at '.leastnthreedifferent` batches; of comminuted porcelain'.Ina-Y teriaLLWithf the particles.y of i thev batches:v of; relatively fine; intermediate, and relatively.: coarse. grain. sizesand*` of different. colorsf respective-1y,l and with z a liquid `to fornov a. unitary:porcelainmim introducing said mixv intoy the tooth-.cavityr ofl'a; mold, and imposing azvibrating actionvupon the; unitary mix inthe mold cavity to settleiztheb rel:- ativelyr coarse particles at@ the'bottom'bthepar`7 ticles of intermediate-grain sizeiabove saidrelaV tively coarse particles and the relatively fine par-f ticies above said f particles.: ofi intermediate: grain size; whereby-:t0 produce-diierentishades: along different por-tions ofthe toothy and to` compact; the material`y` to theformer` a firm` body.l orf a shape correspondingl to the; shape of" the tooth: cavi-tyrof'ithe mold.

"1; The methodV of forming ay comiminuted mix of material=for:producing"v articles with different posed uponth mix. a predetermined coloring effectinfan articleformed of said mix.

8;-, ThewmethodA according` toA claim '7 wherein the particles of. different sizes are formedby grindingsdifferent batchesof material to different particleasizes, and-wherein the. different colors are.v applied to` the. different. batches .of material priorfto grindingfthe same.

REINER W.` ERDILE.;VA

REFERENCES CITED' The-:followingreferences,are of record in the le ofA this patent:

UNITED STATES PATENTS Number; Name Date Re. 18,626: White .Oct. 18, 1932. 2,165,466 Erdle: July 11, 1939 m1596258` Erdle Apr-9, 1940 

